Originally Posted By: OVERKILL
Originally Posted By: CATERHAM
Hypocritically you're conveniently overlooking the fact that the oil pump will be in by-pass most of the time on the heavy 40 grade oil reducing oil flow.
Duron-E in gas engine?
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That's a rather blanket statement to be making. While this may be the case for certain engine designs it most certainly isn't for many others.
OVERKILL
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Originally Posted By: CATERHAM
Originally Posted By: OVERKILL
Originally Posted By: CATERHAM
Hypocritically you're conveniently overlooking the fact that the oil pump will be in by-pass most of the time on the heavy 40 grade oil reducing oil flow.
IIRC, it is like 80 on the Modular.That's still pretty low for a HTHSV 4.2cP oil not to be in by-pass at normal operating temp's at high rev's.
IIRC a late model Corvette has an 80 psi by-pass and needs oil temp's of 100C to drop out of by-pass on the much lighter M1 0W-40.
OVERKILL
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Originally Posted By: CATERHAM
That's still pretty low for a HTHSV 4.2cP oil not to be in by-pass at normal operating temp's at high rev's.
IIRC a late model Corvette has an 80 psi by-pass and needs oil temp's of 100C to drop out of by-pass on the much lighter M1 0W-40.
Yes just tooling around with the engine at relative low rev's you usually are out of by-pass on a grade or two heavier oil once the oil is up to temperature. But not always. Doug Hillary has mentioned examples from down-under of some Porsche owners using an oil so heavy that even on idle the OP gauge is pegged even once up to temperature.
But the point is, if you can't use high rev's without the oil pump being in by-pass once up to temperature, it's one indicator that the oil is way heavier than necessary even when you're just tooling around below the by-pass point.
With the spec' 2.6cP oil you're going to be comfortably above the recommended OP at the higher rev' test spec' at normal operating temp's. In my experience I can't see how a 4.2cP oil
would not be well into by-pass mode at the same test rpm.
But as you say tooling around in the summer no harm will likely come of it (some engines do tolerate very heavy oil better than others) but make no mistake you're certainly operating in counter-productive territory.
I think, therefore I believe (unqualified!), the point Shannow is repeatedly trying to
make is, and this is not a quote;
"Try and get your thinking away from oil pumps, oil pressure and forget about by-pass for once."
If the concern is lubricating "hydrodynamic" bearings, according to Shannow, I believe his point
is; ensure a supply or reservoir of oil. The self-pumping action of the bearing will
be enough to replace the side leakage. Hydrodynamic bearings are not lubricated by
forcing oil through them.
Now, (the light goes on) a non-Newtonian lubricant's ability to temporary shear may
actually help this self-pumping action.
This self-pumping action can be easily visualized in the elliptical rotation that
is found at the big end of an engine's connecting rod.
As rpm is increased, the bearing pumps more oil.
If the oil is colder, the leakage is less.
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I have a 2004 Focus zetec handbook (Italian market) in front of me ,and oil recommendations goes from 5w-30 A1 (now obsolete and similar in wear resistance to API SN AFAIK), an 5w30 A5 and A3 in SAE 5w30 and even in 5w40 grade. It clearly states that 5w40 A3 oil can be used safely without issues if A5 is out of hand.
So my conclusion from this recommendations is that you can go thicker in bearing and kinematic viscosity, but you cannot go thinner in HT-HS viscosity.
I haven't seen yet that car manufacturer will allow use of oil with lower HT-HS then recommended under any circumstances.
I just read 4 hours worth of three guys arguing over VI.
Then you haven't spent enough time to read it all yet. 
Originally Posted By: chrisri
I haven't seen yet that car manufacturer will allow use of oil with lower HT-HS then recommended under any circumstances.
Originally Posted By: used_0il
I think, therefore I believe (unqualified!), the point Shannow is repeatedly trying to
make is, and this is not a quote;
"Try and get your thinking away from oil pumps, oil pressure and forget about by-pass for once."
If the concern is lubricating "hydrodynamic" bearings, according to Shannow, I believe his point
is; ensure a supply or reservoir of oil. The self-pumping action of the bearing will
be enough to replace the side leakage. Hydrodynamic bearings are not lubricated by
forcing oil through them.
Now, (the light goes on) a non-Newtonian lubricant's ability to temporary shear may
actually help this self-pumping action.
This self-pumping action can be easily visualized in the elliptical rotation that
is found at the big end of an engine's connecting rod.
As rpm is increased, the bearing pumps more oil.
If the oil is colder, the leakage is less.
If you introduce oil in the area of "pmin", there is a suction, that can be 3-4psi, and once primied the bearing can be self sustaining, no oil pressure applied...Engine manufacturers often use a grooved main top shell to move the effective low pressure xone closer to the oil feed hole at TDC.
Then as the oil is dragged around the journal, it's pressure is increased due to hydrodynamics, and some is forced out the sides (side leakage)...That's the pumping action at work. Drawing in at low pressure, and squeezing out in the high pressure zones (couple hundred PSI in the loaded area, pump pressure is doing bupkis about getting the oil into the "wedge")
The bearing will only draw from the reservoir (pressurised gallery in an engine) sufficient oil to replace that lost to side leakage...when it doesn't take it all, that builds pressure in the galleries...you are not "pushing" oil through the bearings, the bearings are drawing what they need.
Some of the oil is obviously retained, and does a couple of tours of duty in the bearing before being the bit that leaks out the side.
The stuff leaking out the side is typically 15-30C higher than the supply temperature, and some of the oil within the bearing, around the journals and shells quite some higher (*)...the engine has done work to spin the journals in a film of oil (like a chinese wrist burn for a bad analogy), and it is this effect that people chase when installing low viscosity oils.My last post was one of those things where you go to bed, think about
a topic, then write it down before the idea vanishes.
Today I got thinking about a few things that came up in the viscosity
discussion.
The non back compatibility of 0W20 vs 5W20 in Hondas could be due to an engine
design issue, as simple as an added groove in the unloaded side of a
hydrodynamic bearing for example.
The trouble I'm having now is trying to think up a way to cover my
"Newtonian" comment, that for some reason entered my head as I was writing
the post.
I have not come up with anything acceptable.
The increase in the oil temperature during it's life cycle in the bearing
clearance in both Newtonian and non-Newtonian engine oils, would be the same,
but the change in viscosity would be different.
Call it non-linear shear rate if you like.
One person who was more than helpful throughout the thread, mentioned that
finished lubricants are a blend of more than one base oil, plus an additive
package that also changes the lubricant's viscosity profile with temperature
change.
Therefore in a finished lubricant, VI is not linear either.
This month issue of "Scientific American" (time issue) states that (one author),
Newtonian laws always have a "time" relevance.
That would be similar to the method of measuring viscosity by flow vs time.
If you put oil on a plain bearing and stick it to a journal, it is almost impossible
to pull it straight off.
You can easily remove the bearing by lifting one end.
I think that I may have painted myself into a corner with this one.
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After reading through the VI discussion, I came to the conclusion that
few, if any points participants agreed on.
One possibility is that the VI scale is not obsolete for the purpose it was intended.
For the comparison of base oils.
The separation of the (non-exotic) base oil groups is determined by VI.
Using the viscosity index specification for profiling the viscosity vs temperature
of a finished lubricant is not possible, unless the lubricant is only operated
between the two temperatures that VI is determined.
Therefore, to accurately predict the viscosity behavior of a chosen lubricant
a "viscosity index profile" value would have to be established using the
extreme temperatures that a lubricant would be operated at.
If a 60C spread was maintained, and raised higher and lower with the lubricant's
bulk temperature, (and you guys are not going to like this pun) you would end up with
a polynomial (or plastic) VI curve.
Or a viscosity index that changes with every, however small, change in temperature.
The SAE grading system, good enough, tells us more about the viscosity
behavior vs temperature than the VI index ever could.
As one person put it; "Don't throw out the baby with the bathwater".
Lastly, I don't believe that mono-grades are all that "Newtonian" anymore.
used_Oil...good points.
If you go back in the board's history, I was a proponent of a "cold pumping" and HTHS as a grading (something like -25 3.6, for something that met the cold pumping performance at -25C, and an HTHS). When you get the mechanics and public used to it, it's a consistent measure...easy for an OEM, in that they decide the HTHS for protection, and you choose the cold end spec based on what your ambient at location is.
...and doesn't beg the question of "what happens if you go below 0W"...
As the the Straights being non newtonian, please elaborate, I'm interested...the requirement is zero VIIs
I knew that question would come at the price of adding the last sentence.
I'm better at game theory.
When Russel Crowe pushed his desk out of the dorm window, the desk, books and chairs
all hit the ground at once.
In human studies, how we act and react to our environment determines what we are.
Who we are is less important.
If you apply that logic to motor oil, how it acts and reacts to it's environment
should describe what it is.
How it became that way is less important.
Some members will use a single brand and type of lubricant to qualify their position
that magically applies to the entire class.
That means I can do the same when it suits my needs.
Petro-Can Duron SAE 30 has a VI of 123
If the product is a stand alone mono-grade engine oil with nothing added to modify
it's viscosity vs temperature, then it is the best deal out there for the price.
How Duron 30 acts and reacts to it's environment determines what it is, but how it got
there, less important.
Can it be determined if a lubricant is Newtonian by how it performs in service?
Looking at it's specs, pour point, VI, and HTHS...it looks great. The HTHS of 3.5 is about the "natural" HTHS for a newtonian oil.
PC straight weights
Versus some that I'm familiar with
Delvac 1300 series
and would like, but don't want 205L of it in the shed.
Delvac 1600 series
The PetroCanada looks like a great lube...I'm getting more impressed with their lineup as I'm exposed to them on BITOG...wonder if they need an Aussie distributor.
Your question has me researching at the moment...not playing games.
PAO (and the PC MSDS mentiones it not), has a naturally high VI, and can have some amazing pour points. It's a compact molecule, that doesn't "puff up" like the VIIs are supposed to do...so using decent percentages of PAO as a VII is more akin to blending basestocks
Go to
http://www.cpchem.com/bl/pao/en-us/Pages/faq.aspx
and charge on down to the "does a high viscosity index always reflect a higher quality base oil"...which indicates that CATERHAM's posit that Mobil race oils are 0W by accident has some merit.
Originally Posted By: used_0il
Petro-Can Duron SAE 30 has a VI of 123
If the product is a stand alone mono-grade engine oil with nothing added to modify
it's viscosity vs temperature, then it is the best deal out there for the price.
Originally Posted By: used_0il
That would be similar to the method of measuring viscosity by flow vs time.
Originally Posted By: Shannow
Given that the HTHS,at 150C IS the high temperature protection, VI based on KV40 and KV100 is hardly a determinant in that equation.
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